Probe apparatus

ABSTRACT

A probe apparatus includes a load port for mounting therein a carrier having therein a plurality of substrates; a plurality of probe apparatus main bodies, each having a probe card having probes on its bottom surface; a substrate transfer mechanism for transferring the substrates between the load port and the probe apparatus main bodies, the substrate transfer mechanism being rotatable about a vertical axis and movable up and down. The substrate transfer mechanism has at least three substrates capable of moving back and forth independently. Further, at least two wafers are received from the carrier by the substrate transfer mechanism, and then are sequentially loaded into the probe apparatus main bodies. The prove apparatus a high throughput increasing a wafer transfer efficiency.

FIELD OF THE INVENTION

The present invention relates to a technique for measuring electricalcharacteristics of a target object by bringing probes into electricalcontact with electrode pads of the target object.

BACKGROUND OF THE INVENTION

After IC chips are formed on a semiconductor wafer (hereinafter,referred to as “wafer”), a probe test is performed on the wafer by usinga probe apparatus in order to inspect electrical characteristics of theIC chips. The following is a brief description of an inspection flow ofthe wafer in this probe apparatus. First of all, a wafer is unloaded bya transfer mechanism from a carrier where a plurality of wafers areaccommodated. Next, a position alignment process called as apre-alignment process and a process for acquiring an ID or the likeformed on the wafer which is called as an OCR process are performed onthe wafer. Thereafter, the wafer is loaded into a probe apparatus mainbody, and then is mounted on a wafer chuck capable of moving in X, Y andZ directions and rotating about a Z axis. Next, electrode pads formed onthe wafer and probes of a probe card provided above the wafer chuck areimaged by an upper camera provided above the probe apparatus main bodyto face the wafer chuck and a lower camera provided at the wafer chuck,respectively. Then, a fine alignment process for precisely aligning thepositions of the electrode pads and the probes is performed. Thereafter,in a state where the probes, e.g., probe needles, are brought intocontact with the electrode pads of the IC chips of the wafer, electricalsignals are transmitted from the probe needles to the electrode pads,thereby inspecting electrical characteristics of the IC chips.

The inspection of the electrical characteristics includes severalprocesses and thus requires a long period of time. Thus, in order toincrease a throughput, it is preferable to minimize waiting time of theprobe apparatus main body (during which the inspection is notperformed). To be specific, the transfer mechanism is provided with aloading arm for transferring a wafer to be inspected from the carrierand into the probe apparatus main body and an unloading arm forreturning an inspected wafer from the probe apparatus main body to thecarrier, the loading and the unloading arm being movable independently.During the wafer inspection, a wafer to be inspected is taken out fromthe carrier, and the pre-alignment process or the OCR process isperformed in advance on the corresponding wafer. After the inspectedwafer is unloaded from the probe apparatus main body, the wafer to beinspected is immediately loaded into the probe apparatus main body.Accordingly, it is possible to reduce the waiting time of the probeapparatus main body which is required in exchanging wafers.

In this probe apparatus, in order to reduce a foot space, a pluralityof, e.g., two, probe apparatus main bodies are provided at a commontransfer mechanism, and wafers are transferred by the common transfermechanism to and from the probe main body apparatuses. The following isa specific description of an exemplary case where wafer inspections areindividually performed in the two probe apparatus main bodies. Forexample, a single wafer is unloaded from the carrier, and thepre-alignment process and the OCR process are performed on this wafer.Next, the wafer is exchanged with an inspected wafer in, e.g., one probeapparatus main body, and the inspected wafer is returned to the carrier.Thereafter, a wafer to be inspected is unloaded from the carrier, andthe pre-alignment process and the OCR process are performed on thiswafer. This wafer is exchanged with an inspected wafer in, e.g., theother probe apparatus main body. In this probe apparatus configured asdescribed above, the wafers are transferred by the common transfermechanism to and from the two probe apparatus main bodies, so that afoot space occupied by one transfer mechanism can be reduced. As aresult, the foot space of the probe apparatus can also be reduced.

However, after a wafer in one probe apparatus main body is exchanged, along period of time is required until a wafer in the other probeapparatus main body is exchanged, because there arises a need to accessto the carrier and perform the pre-alignment process or the OCR process.Therefore, when a wafer in one probe apparatus main body is beingexchanged after the inspection, if the inspection of a wafer in theother probe apparatus main body has also been completed, the other probeapparatus main body waits for a long period of time until a wafer in theother probe apparatus main body is exchanged, which deteriorates thethroughput.

Meanwhile, there is known a method in which the loading and theunloading arm are provided with separate driving units so that they canmove independently. In this method, a loading/unloading of a waferto/from the carrier and a loading/unloading of a wafer to/from the probeapparatus main bodies are carried out by different arms. To be specific,a wafer is unloaded from the carrier by the unloading arm, and the waferis transferred from the unloading arm to the loading arm. Next, thewafer is loaded into the probe apparatus main body by the loading arm.Therefore, while the loading arm accesses to a probe apparatus mainbody, the unloading arm can take out a next wafer from the carrier.Accordingly, the transfer time of the wafer decreases and, further, thewaiting time of the probe apparatus main body decreases. However, inthis configuration, the loading and the unloading arm are provided withseparate driving units as described above, so that a cost of the probeapparatus increases and, also, an operation sequence of the arms becomescomplicated.

Although a substrate transfer unit having a plurality of arms isdisclosed in Japanese Patent Laid-open Publication No. 2001-250767, aspecific operation sequence of the arms or the like in the probeapparatus is not described at all.

In order to perform the fine alignment, there arises a need to ensure amovement region of the wafer chuck in the probe apparatus main body.However, as the wafer is scaled up, the movement region is expanded, sothat the apparatus is scaled up. Further, the expansion of the movementregion of the wafer chuck increases movement time and alignment time.Meanwhile, a demand for an improvement of throughput leads to adevelopment of a loader unit capable of loading a plurality of carriersor a common loader unit shaped by a plurality of inspection units.However, there is a trade-off relationship between a high throughput anda large occupation area of the apparatus.

As for a conventional probe apparatus aimed to provide a highthroughput, there is known an apparatus described in Japanese PatentLaid-open Publication No. H6-66465. In this apparatus, two inspectionunits including a wafer chuck, a probe card and the like are connectedto both sides of a loader unit. Since, however, the inspection units arenot designed to be scaled down, the inspection units installed at bothsides of the loader unit increase the occupation area of the apparatus.Further, the wafer transfer deteriorates due to the presence of apincette for transferring a wafer from/to a carrier loaded into theloader unit and two swing arms for transferring the wafer between thepincette and the two inspection units, the pincette being movable in alongitudinal direction of the loader unit. Moreover, the moving paths ofthe swing arms need to be ensured, so that the apparatus cannot bescaled down.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a miniaturizedprobe apparatus capable of providing a high throughput and also capableof improving a throughput by increasing a wafer transfer efficiency.

In accordance with an aspect of the present invention, there is provideda probe apparatus for inspecting a plurality of chips arranged on asubstrate by mounting the substrate on a horizontally and verticallymovable substrate mounting table and then contacting probes of a probecard with electrode pads of the chips, the probe apparatus including: aload port for mounting therein a carrier having therein a plurality ofsubstrates; a plurality of probe apparatus main bodies, each having theprobe card having the probes on its bottom surface; a substrate transfermechanism for transferring the substrate between the load port and theprobe apparatus main bodies, the substrate transfer mechanism beingrotatable about a vertical axis and movable up and down, and a controlunit for outputting a control signal to the probe apparatus main bodiesand the substrate transfer mechanism.

The substrate transfer mechanism has at least three substrate supportingmembers, each being independently movable back and forth, and thecontrol unit outputs a control signal for receiving at least twosubstrates to be inspected from the carrier by the substrate transfermechanism and sequentially replacing with inspected substrates in theprobe apparatus main bodies by using the empty substrate supportingmember or members.

The substrate transfer mechanism may includes a pre-alignment mechanismhaving a rotation unit which rotates a substrate received from thesubstrate supporting members and a detection unit which irradiates lightto a region including a circumferential edge portion of the substrate onthe rotation unit and receives light passing through the correspondingregion in order to position-align the substrate.

The present invention provides a probe apparatus including: a load portfor mounting thereon a carrier having therein a plurality of substrates;a plurality of probe apparatus main bodies, each having a probe cardhaving on its bottom surface probes; and a substrate transfer mechanismfor transferring the substrate between the load port and the probeapparatus main bodies. In this probe apparatus, the substrate transfermechanism is provided with at least three substrate supporting memberscapable of moving back and forth independently. Further, at least twosubstrates are received from the carrier by the substrate transfermechanism, so that at least two substrates can be sequentially replacedwith inspected substrates in the probe apparatus main bodies by using anempty substrate supporting member. Accordingly, the waiting time of theprobe apparatus main bodies can be reduced, thereby improving athroughput.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become apparentfrom the following description of embodiments, given in conjunction withthe accompanying drawings, in which:

FIG. 1 is a general perspective view of an example of a probe apparatusin accordance with a first embodiment of the present invention;

FIG. 2 describes a schematic top view of the example of the probeapparatus;

FIG. 3 provides a vertical cross sectional view of the example of theprobe apparatus;

FIG. 4 presents a perspective view of an example of a load port in theprobe apparatus;

FIG. 5 presents a schematic view of an example of a wafer transfermechanism in the probe apparatus;

FIG. 6 offers a perspective view of an example of an inspection unit inthe probe apparatus;

FIGS. 7A and 7B show schematic views of the example of the inspectionunit;

FIG. 8 illustrates a position of an alignment bridge in the inspectionunit;

FIG. 9 depicts a schematic view of an example of a movement stroke of awafer chuck in the inspection unit;

FIG. 10 is a top view showing an exemplary operation of the probeapparatus;

FIG. 11 shows a top view illustrating an exemplary operation of theprobe apparatus;

FIG. 12 illustrates a top view depicting an exemplary operation of theprobe apparatus;

FIG. 13 depicts a top view describing an exemplary operation of theprobe apparatus;

FIG. 14 presents a top view of a movement stroke of a wafer chuck whichis obtained when specific points on a wafer are imaged by a secondimaging unit;

FIG. 15 presents a schematic view of a movement stroke of a wafer chuckin case of using a conventional probe cared for multiple contacts;

FIG. 16 describes a vertical cross sectional view of a probe apparatusin a modification of the first embodiment;

FIGS. 17A and 17B show schematic views of a wafer transfer mechanism inthe modification;

FIG. 18 illustrates a top view of an operation of the probe apparatus inthe modification;

FIG. 19 is a side view of a probe card which indicates an example of areplacement mechanism of the probe card in the inspection unit;

FIG. 20 is the side view of the probe card which shows the example ofthe replacement mechanism of the probe card;

FIG. 21 is a side view of the probe card which depicts an example of thereplacement mechanism of the probe card;

FIG. 22 is a side view of a probe card which describes an example of aconventional probe card replacement mechanism;

FIG. 23 provides a top view of another configuration example of theprobe apparatus;

FIG. 24 shows a top view of another configuration example of the probeapparatus;

FIG. 25 offers a top view of an example of a layout of the probeapparatus;

FIG. 26 illustrates a top view of an example of the layout of the probeapparatus;

FIG. 27 presents a top view of another configuration example of theprobe apparatus;

FIG. 28 offers a top view illustrating a position of an alignment bridgein the inspection unit of the probe apparatus;

FIG. 29 represents a top view of another configuration example of theprobe apparatus;

FIGS. 30A and 30B show schematic views of an example of a shutter in theprobe apparatus;

FIGS. 31A and 31B illustrate schematic views of another example of theinspection unit;

FIG. 32 sets forth a top view depicting a movement stroke of a microcamera in the first embodiment;

FIG. 33 illustrates a top view of a movement stroke of a micro camera inanother example;

FIGS. 34A and 34B provide schematic views of another example of theinspection unit;

FIGS. 35A and 35B are top views of an example of a process for replacinga probe card in a probe apparatus main body;

FIG. 36 explains a sequence of transferring a wafer by using a wafertransfer mechanism in accordance with the embodiment of the presentinvention;

FIG. 37 explains a sequence of transferring a wafer by using the wafertransfer mechanism in accordance with the embodiment of the presentinvention;

FIG. 38 explains a sequence of transferring a wafer by using a wafertransfer mechanism having two arms;

FIG. 39 explains a sequence of transferring a wafer by using the wafertransfer mechanism having two arms;

FIG. 40 illustrates an example of a configuration of a control unit inaccordance with the embodiment of the present invention;

FIG. 41 explains a part of a manipulation display used in the controlunit;

FIG. 42 depicts a top view of another example of the alignment bridge inaccordance with the embodiment of the present invention;

FIGS. 43A and 43B explain a movement of the wafer chuck in case of usingthe alignment bridge;

FIG. 44 explains an entire moving amount of a wafer W in an X directionin case of using the alignment bridge;

FIG. 45 explains an entire moving amount of the wafer W in the Xdirection in case of using an alignment bridge to which a single microcamera is attached;

FIG. 46 explains a method of using the micro camera of the alignmentbridge;

FIGS. 47A and 47B explain a method of using the micro camera of thealignment bridge;

FIGS. 48A and 48B explain a method of using the micro camera of thealignment bridge;

FIGS. 49A to 49F are schematic views of an example of an operationsequence of the wafer transfer mechanism in accordance with theembodiment of the present invention;

FIGS. 50A to 50G are schematic views of an example of an operationsequence of a conventional wafer transfer mechanism; and

FIG. 51 offers a schematic view illustrating a sequence of time to movethe wafer transfer mechanism or to perform processes which is actuallyobtained in the embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. However, the presentinvention is not limited thereto.

First Embodiment

As illustrated in FIGS. 1 to 3, a probe apparatus in accordance with afirst embodiment of the present invention includes: a loader unit 1 fortransferring a wafer W as a substrate having thereon a plurality ofchips to be inspected; and a probe apparatus main body 2 for probing thewafer W. Above all, entire layout of the loader unit 1 and the probeapparatus main body 2 will be described briefly.

The loader unit 1 has a first and a second loading port 11 and 12 forloading a first and a second carrier C1 and C2 as transfer containersaccommodating therein a plurality of wafers W and a transfer chamber 10provided between the first and the second loading port 11 and 12. Thefirst and the second loading port 11 and 12 have a first and a secondmounting table 13 and 14 spaced from each other in a Y direction, andthe first and the second mounting table 13 and 14 mount thereon thecarriers C1 and C2 so that transfer openings (front openings) thereofcan face each other. Further, the transfer chamber 10 is provided with awafer transfer mechanism (substrate transfer mechanism) 3 whichtransfers the wafer W by using an arm 30 as a substrate supportingmember.

The probe apparatus main body 2 has a housing 22 forming a casing of theprobe apparatus main body 2. The housing 22 is provided near the loaderunit 1 in an X direction, and is divided into two sections in the Ydirection via a partition wall 20. The two sections correspond tocasings of a first and a second inspection unit 21A and 21B. The firstinspection unit 21A has a wafer chuck 4A as a substrate mounting table,an alignment bridge 5A serving as an imaging unit having a camera movingin the Y direction above the wafer chuck 4A, and a probe card 6Aprovided in a head plate 201 forming a ceiling portion of the housing22. The second inspection unit 21B has the same configuration whichincludes a wafer chuck 4B, an alignment bridge 5B and a probe card 6B.

Hereinafter, the loader unit 1 will be described. Since the first andthe second loading port 11 and 12 are symmetrically arranged and have asame configuration, the configuration of the first loading port 11 isrepresentatively described in FIG. 4. As shown in FIGS. 3 and 4, theloader unit 1 is partitioned from the transfer chamber 10 by a partitionwall 20 a, and the partition wall 20 a is provided with a shutter S andan opening/closing mechanism (not shown) for opening and closing theshutter S and the transfer port of the first carrier C1. Moreover, thefirst mounting table 13 is configured to rotate by an interval of 90° ina clockwise direction and a counterclockwise direction by a rotationmechanism (not shown) positioned therebelow.

Namely, when the airtight carrier C1 called a FOUP (Front OpeningUnified Pod) is mounted on the first mounting table 13 from the frontside of the probe apparatus (right side of the X direction) by anautomatic guided vehicle (AGV) (not shown) in a clean room in a statewhere the front opening of the carrier C1 faces the probe apparatus(left side of the X direction), the first mounting table 13 rotates byan angle of 90° in the clockwise direction so that the opening can facethe shutter S. Meanwhile, when the first carrier C1 is unloaded from thefirst mounting table 13, the first carrier C1 rotates by an angle of 90°in the counterclockwise direction.

The wafer W is transferred between the first carrier C1 and the wafertransfer mechanism 3 by moving back and forth the wafer transfermechanism 3 with respect to the first carrier C1. At this time, thefirst carrier C1 communicates with the transfer chamber 1 by opening theshutter S and the transfer opening of the first carrier C1 with the useof the opening/closing mechanism 20 b in a state where the opening ofthe first carrier C1 faces the shutter S.

The wafer transfer mechanism 3 includes a transfer base 35, a rotationaxis 3 a for rotating the transfer base 35 about a vertical axis, and alift mechanism (not shown) for vertically moving the rotation axis 3 a.The transfer base 35 has three arms 30, and each of the arms 30independently moves back and forth to transfer the wafer W. The rotationcenter of the rotation axis 3 a is positioned between the first and thesecond carrier C1 and C2. That is, the rotation center is spaced apartat the same distance from the first and the second carrier C1 and C2.Further, the wafer transfer mechanism 3 can move vertically between anupper position where the wafer W is transferred between the first andthe second carrier C1 and C2 and a lower position where the wafer W istransferred between the first and the second inspection unit 21A and21B.

In a lower portion of the transfer chamber 10, a pre-alignment mechanism39 for pre-aligning the wafer W is installed at a position that does notinterfere with an operation of the wafer transfer mechanism 3, e.g., ata position spaced from a rotation center of the wafer transfer mechanism3 toward the second mounting table 14. The pre-alignment mechanism 39includes: a rotation table 500 which mounts thereon the wafer W androtates the wafer W about a vertical axis; an optical sensor 37 as adetection unit having a light emitting portion and a light receivingportion which are installed so that an area including a circumferentialedge portion of the wafer mounted on the rotation table 500 ispositioned therebetween; and a base 501 for supporting the rotationtable 500 and the optical sensor 37 from the bottom. The rotation table500 is configured to have a width dimension smaller than an openingdimension of a cutoff portion formed at a leading end of the arm 30 sothat the rotation table 500 can be inserted into the cutoff portion. Inaddition, although it is not shown, the loader unit 1 further includes acontroller for detecting a central position of the wafer W and adirection reference such as notches or orientation flats of the wafer Wbased on a detection signal from the optical sensor 37 and then rotatingthe rotation table 500 based on the detection result so that the notchesor the like can be oriented in a predetermined direction.

The following is a brief description of a process for adjusting(pre-aligning) the orientation of the wafer W by the pre-alignmentmechanism 39 including the optical sensor 37 and the rotation table 500.First of all, the wafer W is mounted on the rotation table 500 by thewafer transfer mechanism 3. Next, the wafer W is rotated by the rotationtable 500 and, at the same time, light is emitted from the lightemitting portion of the optical sensor 37 toward the light receivingportion via the area including the circumferential edge portion (endportion) of the wafer W. A locus of the circumferential edge portion ofthe wafer W is read by the optical sensor 38, so that the orientationand the central position of the wafer W are recognized.

Further, the rotation table 500 is made to stop in a state where thewafer W is positioned in a predetermined orientation on the rotationtable 500 and, then, the wafer W is transferred to the wafer transfermechanism 3. In this way, orientation of the wafer W is adjusted.Thereafter, the position of the wafer transfer mechanism 3 is adjustedso that eccentricity of the wafer W can be corrected when the wafer W ismounted on the wafer chuck 4A of the first inspection unit 21A forexample. In this manner, the orientation and the eccentricity of thewafer W are adjusted.

Although it is not shown, an OCR mechanism (cassette) including, e.g., acamera and the like, for checking an ID such as an object identificationmark or the like formed on, e.g., the surface of the wafer W, isprovided in the transfer chamber 10. The ID is acquired after, e.g., thepre-alignment process.

Hereinafter, the probe apparatus main body 2 will be described. In thehousing 22 of the probe apparatus main body 2, a strip-shaped transferopening 22 a extending in a horizontal direction (Y direction) opens ina sidewall of the loader unit 1 side, to thereby transfer the wafer Wfrom/to the first inspection unit 21A or the second inspection unit 21B.In the first and the second inspection unit 21A and 21B, the positionsfor transferring wafers W, the positions for imaging surfaces of thewafers W and the positions for installing the respective probe cards 6Aand 6B are symmetrical with respect to a horizontal line HLperpendicular to a straight line connecting the first and the secondloading port 11 and 12 via the rotation center of the wafer transfermechanism 3. Further, since the first and the second inspection unit 21Aand 21B have a same configuration, the first inspection unit 21A will berepresentatively described with reference to FIGS. 3, 6 and 7.

The inspection unit 21A has a base 23. Further, a Y stage 24 and an Xstage 25 are provided on the base 23 in that order. The Y stage 24 isdriven in the Y direction by, e.g., a ball screw or the like, along aguide rail extending in the Y direction, and the X stage 25 is driven inthe X direction by, e.g., a ball screw, along a guide rail extending inthe X direction. Although it is not shown, the X stage 25 and the Ystage 24 have motors combined with encoders.

Provided on the X stage 25 is a Z moving unit 26 moving in a Z directionby a motor combined with an encoder (not shown). The Z moving unit 26has a wafer chuck 4A serving as a substrate mounting table capable ofrotating about a Z-axis (moving in a θ direction), so that the waferchuck 4A can move in X, Y, Z and θ directions. A driving unit is formedby the X stage 25, the Y stage 24 and the Z moving unit 26, and isconstructed to move the wafer chuck 4A among the transfer positions fortransferring the wafer W with respect to the wafer transfer mechanism 3,the imaging positions on the surface of the wafer W and the contactpositions (inspection positions) of the probe needles 29 of the probecard 6A, as will be described later.

The probe card 6A is detachably adhered to the head plate 201 above themovement region of the wafer chuck 4A. The adhesion structure or thereplacement method of the probe card 6A will be described later. Theprobe card 6A has on a top surface thereof an electrode group. Further,a pogo pin unit 28 having on a bottom surface thereof a plurality ofpogo pins 28 a as an electrode unit positioned corresponding to theelectrode group of the probe card 6A is provided above the probe card 6Ato electrically connect the electrode group and the test head (notshown). Generally, the test head (not shown) is positioned on the topsurface of the pogo pin unit 28. In this example, however, the test headis separately provided from the probe apparatus main body 2, and isconnected with the pogo pin unit 28 via a cable (not illustrated).

The probes are provided on the entire bottom surface of the probe card6A. The probes, i.e., vertical needles (wire probe needles) areelectrically connected with the electrode group of the top surface ofthe probe card 6A and extend vertically with respect to the surface ofthe wafer W to correspond to the arrangement of the electrode pads ofthe wafer W. As for the probes, there may be used the probe needles 29made of a metal wire extending downward slantingly with respect to thesurface of the wafer W, a gold bump electrode formed on a flexible filmor the like. The probe card 6A in this example is configured to make acontact with all the electrode pads of the chips to be inspected (ICchips) on the wafer surface at a time, so that the electricalcharacteristics can be measured by a single contact operation.

A micro camera 41 having an upward view, i.e., a first imaging unit forimaging the probe needles 29, is fixed via a fixing plate 41 a to a sideportion of the Z moving unit 26, the side portion facing toward thepartition wall 20 of the wafer chuck 4A. The micro camera 41 is formedas a high magnification camera having a CCD camera so that an enlargedview of a needle tip of a probe needle 29 or an alignment mark of theprobe card 6A can be obtained. Moreover, the micro camera 41 ispositioned substantially at the center point in the X direction of thewafer chuck 4A. In order to check the arrangement and the positions ofthe probe needles 29 during the alignment, the micro camera 41 imagesspecific probe needles 29, e.g., the probe needles 29 positioned at bothends of the X and Y directions. Further, in order to monitor the statesof the probe needles 29 regularly, the micro camera 41 images all theprobe needles 29 sequentially.

A micro camera 42 as a low magnification camera for imaging thearrangement of the probe needles 29 in a wide area is fixed to thefixing plate 41 a near the micro camera 41. In addition, a target 44 isprovided on the fixing plate 41 a so that it can move back and forth bya reciprocating mechanism 43 in a direction perpendicular to an opticalaxis with respect to an in-focus surface of the micro camera 41. Thetarget 44 can be recognized through an image by the micro camera 41 anda micro camera 45 to be described later. Moreover, the target 44 has astructure that a circular metallic film as a subject for alignment,e.g., a metallic film having a diameter of about 140 micron, isdeposited on, e.g., a transparent glass plate. FIGS. 7A and 7B provide atop view and a side view schematically describing a positionalrelationship between the wafer chuck 4A and the micro cameras 41 and 42.The target 44 or the reciprocating mechanism 43 is omitted in FIGS. 7Aand 7B.

Guide rails 47 are provided along the Y direction on both sides (frontside and inner side) in the X direction of an inner wall surface of thehousing 22 between the wafer chuck 4A and the probe card 6A. Asillustrated in FIG. 8, the alignment bridge 5A as an imaging unit canmove in the Y direction along the guide rail 47 between a referenceposition to be described later and the imaging position.

The alignment bridge 5A has a plurality of, e.g., three, micro cameras45 having a downward view. The three micro cameras 45 serve together asa second imaging unit for imaging a substrate, and are spaced from eachother at regular intervals along the X direction. The central microcamera 45 among the three micro cameras 45 is positioned at a centralportion of the movement region of the wafer chuck 4A. The other microcameras 45 positioned at both ends are spaced from the central microcamera 45 at a distance equal to that between the center of the waferchuck 4A and an outermost chip to be inspected of the wafer W or at adistance corresponding to ⅓ of the diameter of the wafer W. These microcameras 45 are high magnification cameras including a CCD camera so thatthe enlarged view of the surface of the wafer W can be obtained.Moreover, the alignment bridge 5A has a low magnification camera 46provided at the Y-axis direction side of the micro cameras 45. The lowmagnification camera 46 is illustrated only in FIG. 2.

A reference position corresponding to the stop position of the alignmentbridge 5A is a position at which the alignment bridge 5A retreats toavoid the contact with the wafer chuck 4A or the wafer transfermechanism 3 when the wafer W is transferred between the wafer chuck 4Aand the wafer transfer mechanism 3, when the wafer W is brought intocontact with the probe card 6A and when the probe needles 29 are imagedby the first imaging unit (micro camera 41). Moreover, the imagingposition is a position obtained when the surface of the wafer W isimaged by the low magnification camera 46 and the micro cameras 45 ofthe alignment bridge 5A. The surface of the wafer W is imaged by themicro cameras 45 and the low magnification camera 46 while moving thewafer chuck 4A in a state where the alignment bridge 5A is fixed to theimaging position.

As can be seen from FIG. 8 and a lower portion of FIG. 9, the imagingposition is deviated toward an inner side of the Y direction (toward thecenter of the probe apparatus main body 2) with respect to the centralposition of the probe card 6A. The reason thereof will be described asfollows.

As set forth above, when the probe needles 29 are imaged by the microcamera 41 provided on a side surface of the wafer chuck 4A (front sideof the Y-axis direction), a movement stroke D2 in the Y-axis directionof the wafer chuck 4A (a movement stroke of a central position O1 of thewafer chuck 4A) is deviated toward the partition wall 20 side of theY-axis direction with respect to a central position O2 of the probe card6A, as shown in a middle portion of FIG. 9.

Meanwhile, as illustrated in an upper diagram of FIG. 9, a movementstroke D1 of the wafer chuck 4A at which the wafer W contacts with theprobe needles 29 is short, because a plurality of probe needles 29 isformed on the bottom surface of the probe card 6A, so that the probeneedles 29 are brought into contact with the wafer W at a time.Accordingly, when the imaging position of the alignment bridge 5A isaligned with the central position O2 of the probe card 6A, a movementstroke D3 of the wafer chuck 4A at which the surface of the wafer W isimaged by the micro camera 45 is deviated toward the right side of themovement stroke D1.

Therefore, the imaging position of the alignment bridge 5A is made to bebiased toward the partition wall 20 side of the Y-axis direction so thatthe movement strokes D2 and D3 are overlapped with each other, therebyshortening a driving stroke (movable range) D4 including the movementstrokes D1 to D3 of the wafer chuck 4A, i.e., a distance in the Y-axisdirection of the probe apparatus main body 2. The movement strokes D2and D3 may not be the same as long as the imaging position of thealignment bridge 5A is deviated toward the partition wall 20 side of theY-axis direction with respect to the central position O2 of the probecard 6A.

As shown in FIG. 2, the probe apparatus includes a control unit 15 whichis, e.g., a computer. The control unit 15 has a data processing unitformed of a program, a memory, a CPU or the like. The program hasmultiple steps for controlling a series of operations of each unit whichincludes loading of the carrier C into the loading port 11 or 12,inspecting the wafer W, returning the wafer W to the carrier C andunloading the carrier C. Further, the program (including a program formanipulating input or displaying) is stored in a storage medium 16,e.g., a flexible disk, a compact disk, an MO (magneto-optical) disk, ahard disk or the like, and is installed in the control unit 15.

Hereinafter, the operation of the probe apparatus will be described.First of all, the carrier C is loaded from the opposite side of theprobe apparatus main body 2 into the loading port 11 or 12 by the AGV ina clean room. At this time, the transfer opening of the carrier C facesthe probe apparatus main body 2. However, the transfer opening of thecarrier C is made to face the shutter S by rotating the mounting table13 or 14. Next, the mounting table 13 moves forward, so that the carrierC is pushed toward the shutter S. As a result, the lid of the carrier Cand the shutter S are separated.

Thereafter, the wafer W is unloaded from the carrier C, and istransferred to the inspection unit 21A or 21B. Since the two wafers W1and W2 are already inspected by the first and the second inspection unit21A and 21B, the process for unloading next wafers W3 and W4 from thecarrier C will be described hereinafter.

Above all, the upper arm 31 moves into the second carrier C2 to receivethe wafer W3, and then is retreated, as illustrated in FIG. 10. Next,the middle arm 32 moves into the second carrier C2 to receive the waferW4, and then is retreated. The wafer transfer mechanism 3 moves downand, at the same time, the arms 31 and 32 rotate in an orientation toaccess the rotation table 500. Thereafter, the upper arm 31 extendstoward the rotation table 500 until the wafer W3 mounted thereon ispositioned above the rotation table 500, as shown in FIG. 11.

Next, the wafer transfer mechanism 3 moves slightly down, so that thewafer W3 is mounted on the rotation table 500. When the rotation table500 rotates, the optical sensor 37 emits light to the area including acircumferential edge portion of the wafer W3, and then receives thelight passing through the area including the correspondingcircumferential edge portion. The orientation of the wafer W3 isadjusted such that the notch is oriented to correspond to the first orsecond inspection unit 21A or 21B into which the wafer W3 will be loadedbased on the detection result of the optical sensor 37.

Further, the eccentricity of the wafer W3 is detected. In this way,pre-alignment is performed. Next, the wafer transfer mechanism 3 movesup to receive the wafer W3. In the same manner, the notch direction ofthe wafer W4 is controlled to correspond to the first or secondinspection unit 21A or 21B where the wafer W4 will be inserted and theeccentricity of the wafer W4 is detected. Further, the IDs formed on thesurfaces of the wafers W3 and W4 are acquired by the aforementioned OCRmechanism (not shown).

Next, the wafer W1 in the first inspection unit 21A is replaced with thewafer W3 mounted on the wafer transfer mechanism 3. FIGS. 49A to 49F forexplaining an embodiment to be described later schematically illustratea series of operations of the wafer transfer mechanism 3. If theinspection of the wafer W1 is completed, the wafer chuck 4A moves to thetransfer position near the partition wall 20, as can be seen from FIG.12. Thereafter, the vacuum chuck of the wafer chuck 4A is released, andthe lift pin in the wafer chuck 4A is moved up to raise the wafer W1.The empty lower arm 33 moves about the wafer chuck 4A, and the wafertransfer mechanism 3 moves up, and, then, the upper arm 31 receives thewafer W1 and retreats. Next, the wafer transfer mechanism 3 movesslightly down, and the upper arm 31 moves about the wafer chuck 4A. Ifit is determined that the central position of the wafer W3 is deviatedin the pre-alignment, the wafer W3 is mounted on the wafer chuck 4A bythe cooperation of the lift pin (not shown) and the upper arm 31 so thatthe eccentricity of the wafer W3 can be corrected.

Thereafter, as shown in FIG. 13, the upper arm 31 that has become emptyafter the wafer W3 is transferred to the first inspection unit 21A movesinto the second inspection unit 21B. Next, the upper arm 31 receives thewafer W2 inspected on the wafer chuck 4B and retreats. Thereafter, themiddle arm 32 moves onto the wafer chuck 4B, and the wafer W4 to beinspected is transferred from the middle arm 32 to the wafer chuck 4B.

Next, the wafer transfer mechanism 3 moves up, and the wafers W1 and W2are returned to, e.g., the first carrier C1. Besides, next wafers W5 andW6 are unloaded from the carrier C to be subjected to the sameprocesses.

Meanwhile, in the first inspection unit 21A, after the wafer W3 istransferred to the wafer chuck 4A, the probe needles 29 of the probecard 6A are imaged by the micro camera 41 provided at the wafer chuck4A. To be specific, the probe needles 29 positioned at both ends of theX direction and those positioned at both ends of the Y direction areimaged, thereby checking the center of the probe card 6A and thearrangement of the probe needles 29. In this case, the needle tippositions of the target probe needles 29 in a region near a targetposition which is determined by the micro camera 42 are detected by themicro camera 41. At this time, the alignment bridge 5A is retreated tothe reference position depicted in FIG. 8.

Next, the alignment bridge 5A moves to the imaging position of the waferW3 (see FIG. 8) and, at the same time, the target 44 (see FIG. 6) ismade to project to an area between the micro camera 41 of the waferchuck 4A and the micro cameras 45 of the alignment bridge 5A.Thereafter, the position of the wafer chuck 4A is adjusted so that thefocuses and the optical axes of the micro cameras 41 and 45 coincidewith the target mark of the target 44. As a result, the original pointof the micro cameras 41 and 45 is obtained.

After the target 44 is retreated, the wafer chuck 4A is positioned underthe alignment bridge 5A. In that state, the wafer chuck 4A moves so thata plurality of specific points formed on the wafer W3 can be imaged byany one of the three micro cameras 45 of the alignment bridge 5A. Inthis case, the wafer chuck 4A is guided to a vicinity of a target areaon the wafer W, based on the imaging result of the micro camera 46.

In this example, the three micro cameras 45 are spaced from each otherat the distance corresponding to ⅓ of the diameter of the wafer W3.Therefore, even if the entire surface of the wafer W is sequentiallyimaged by the micro cameras 45, the movement distance of the wafer W3 inthe X direction (the driving amount of the ball screw which is requiredto move the X stage 25) corresponds to a movement distance L1 of thecenter of the wafer chuck 4A between a position where the micro camera45 provided at one end side is overlapped with one end portion of thewafer W3 and a position where the micro camera 45 provided at the otherend side is overlapped with the other end portion of the wafer W3 asillustrated in FIG. 14, i.e., a distance corresponding to ⅓ of thediameter of the wafer W3. Accordingly, even if the specific points onthe wafer W3 are positioned on the circumference of the wafer W3, themovement distance of the wafer chuck 4A in the X direction decreases.

Based on the position of the wafer chuck 4A at which the imaging isperformed and the position of the wafer chuck 4A at which the originalposition is obtained, the control unit 15 can calculate coordinates ofthe wafer chuck 4A at which the probe needles 29 of the probe card 6Acontact with the electrodes pads on the wafer W3. By moving the waferchuck 4A to the calculated contact position, the probe needles 29 of theprobe card 6A are brought into contact with the electrode pads on thewafer W3 at a time.

Further, a predetermined electrical signal is transmitted from the testhead (not shown) to the electrode pads of the IC chips on the wafer W3via the pogo pin unit 28 and the probe card 6A, thereby testingelectrical characteristics of the IC chips. Thereafter, as in the caseof the wafer W1, the wafer W3 is unloaded from the wafer chuck 4B by thewafer transfer mechanism 3 while moving the wafer chuck 4B to thetransfer position. In the same manner, the wafer W4 loaded into thesecond inspection unit 21B is inspected0048

In accordance with the above embodiment, the wafer transfer mechanism 3is provided with the three arms 30 (31-33), and two wafers W to beinspected are received from the carrier C by the wafer transfermechanism 3. Accordingly, the wafers W can be sequentially transferredto the two inspection units 21, thus reducing the waiting time of theinspection units 21 and improving the throughput of the probe apparatus.For example, when the wafers W1 and W2 are transferred (when theinspection of the wafers W is started in the probe apparatus), thewafers W1 and W2 can be sequentially transferred to the two inspectionunits 21.

Therefore, the inspection in the inspection units 21 can be startedquickly and, hence, the throughput can be improved. Moreover, when thewafers W are exchanged as in the conventional example, a wafer W to beinspected can be subjected to a pre-alignment process or the like whilea wafer W is being inspected in the inspection units 21. Thus, thewafers W can be exchanged immediately after the inspection is completedand the waiting time of the inspection units 21 can be further reduced.

Different from the conventional example, in this embodiment, the arm fortransferring the wafer W to the inspection units 21 is not distinguishedfrom the arm for unloading the wafer W from the inspection units 21. Forexample, an inspected wafer W is unloaded by using an empty arm 33 thatdoes not transfer the wafer W among the three arms 30. That is, since nowafer W is mounted on the lower arm 33, the wafer W1 can be received bythe lower arm 33 in the first inspection unit 21A. Further, the wafer W3on the upper arm 21 is loaded into the first inspection unit 21A afterunloading the wafer W1 therefrom. Then, the inspected wafer W2 can bereceived by the empty upper arm 21 in the second inspection unit 21B.Accordingly, the efficiency of transferring the wafer W can be increased(transfer time of the wafer W can be reduced), as described above. Thatis, a plurality of wafers W can be exchanged only by using the empty arm33 provided only by increasing the member of arms 30 by one compared tothe number of wafers W to be transferred. As a result, the scaling up ofthe wafer transfer mechanism 3 can be suppressed.

Moreover, the present invention includes the first and the secondloading port 11 and 12 for mounting therein two carriers C facing eachother, the wafer transfer mechanism 3 having the rotation center betweenthe loading ports 11 and 12, and the first and the second inspectionunit 21A and 21B being symmetrical to each other and disposed inaccordance with the arrangement of the loading ports 11 and 12. In thefirst and the second inspection unit 21A and 21B, the positions of thewafer chucks 4A and 4B at which the wafers W are transferred, themovement regions of the wafer chucks 4A and 4B at which the wafers W areimaged and the positions of the probe cards 6A and 6B are symmetricalwith respect to the horizontal line HL (see FIG. 2).

In this configuration, the wafers W are directly transferred between thecarrier C and the wafer chuck 4A (or 4B) of the inspection unit 21A (or21B) by the wafer transfer mechanism 3, so that the apparatus can beminiaturized and, also, the substrate transfer efficiency increases. Inaddition, since the wafers W can be simultaneously inspected by thefirst and the second inspection unit 21A and 21B, the substrateinspection efficiency increases. As a result, a high throughput can beachieved.

Moreover, each of the alignment bridges 5A and 5B has the three microcameras 45 spaced apart from each other along the X direction by thedistance corresponding to ⅓ of the diameter of the wafer W. Therefore,the movement region of the wafer chuck 4A or that of the wafer chuck 4Bat which the surface of the wafer W imaged by the cameras 45 can bereduced.

In comparison with the single contact operation, when the contactoperation is performed multiple times, a central position of a movementstroke D1′ of the wafer chuck 4A at which the contact operation isperformed substantially coincides with the central position O2 of theprobe card 50, as can be seen from FIG. 15. Further, since the imagingposition of the alignment bridge 5A is aligned with the central positionof the movement stroke D1′ (the central position O2 of the probe card6A), a movement stroke D3′ at which the wafer W is imaged becomes thesame as the movement stroke D1′ at which the contact operation isperformed. In that case, the probe needles 29 are arranged in a smallregion, so that a movement stroke D2′ of the wafer chuck 4A which isrequired to image the probe needles 29 becomes extremely short.Therefore, a movement stroke D4′ of the wafer chuck 4A which includesthe movement strokes D1′ to D3′ is minimized to be substantially thesame as the driving stroke D4 obtained when using the probe card 6A.

However, if the probe needles 29 formed on the entire surface of thewafer W need to be imaged in a state where the central position of themovement stroke D1′ at which the contact operation is performed isaligned with the central position of the movement stroke D3′ at whichthe wafer W is imaged, a driving stroke D4′ of the wafer chuck 4A needsto be increased to include the movement stroke D2 at which the probeneedles 29 are imaged and, hence, the probe apparatus main body 2 isscaled up. Therefore, in the embodiment of the present invention, asdescribed in FIG. 9, the central portion of the wafer chuck 4A in themovement stroke D2 at which the probe needles 29 are imaged is made tocoincide with that in the movement stroke D3 at which the wafer W isimaged so that the probe apparatus main body 2 can be specialized forthe probe card 6A. Accordingly, the driving stroke D4 of the wafer chuck4A is reduced and, hence, the probe apparatus main body 2 can be scaleddown.

Modification of First Embodiment

Hereinafter, a modification of the first embodiment will be describedwith reference to FIGS. 16 and 17.

In this example, the wafer transfer mechanism 3 includes a pre-alignmentmechanism 39 for pre-aligning the wafer W. The pre-alignment mechanism39 has an axis 36 a that freely rotates and vertically moves up and downthrough the transfer base 35 and a chuck portion 36 provided on top ofthe axis 36 a and serving as a rotation stage. Under normalcircumstances, the chuck portion 36 is engaged into a recess formed inthe surface of the transfer base 35 to form a same plane with thesurface of the transfer base 35. The chuck portion 36 is located at aposition corresponding to a central position of a wafer on one of thearms 30, which are moved back to a middle of a movement route, andserves to lift the wafer W slightly off the arm and rotate it.

The pre-alignment mechanism 39 includes optical sensors 37 and 38 whichserve as a detection unit having a light emitting portion and a lightreceiving portion for detecting a circumference edge of the wafer Wrotated by the chuck portion 36. The optical sensors 37 and 38 are fixedto the transfer base 35 while being deviated from the movement region ofthe arms 30. In this example, the wafers W on the lower and the middlearm 33 and 32 will be pre-aligned, so that the heights of the opticalsensors 37 and 38 are set to avoid the contact with the circumferenceedges of the wafers W during an access to the wafers W while beingpositioned above and below the circumstances edges of the wafers Wlifted by the chuck portion 36.

The following is a brief description of a process for adjusting(pre-aligning) the orientation of the wafer W mounted on the lower arm33 by the pre-alignment mechanism 39 of the present embodiment. In thisexample, the processes other than the pre-alignment process will not beexplained because they are the same as those described in the aboveexample.

First of all, the lower arm 33 moves into the carrier C to receive thewafer W, and then retreats to a position for pre-alignment. Then, asshown in FIG. 18, the wafer W on the lower arm 33 is slightly lifted androtated by the chuck portion 36 and, at the same time, light is emittedfrom the light emitting portion of the optical sensor 38 toward thelight receiving portion via an area including a circumferential edgeportion (end portion) of the wafer W. Next, the chuck portion 36 stopsso that the notch of the wafer W is oriented to correspond to the firstor second inspection unit 21A or 21B into which the wafer W will beloaded based on the detection result of the optical sensor 37.

Then, the chuck portion 36 is lowered, and the wafer W is transferred onthe lower arm 33. As a consequence, the direction of the wafer W isadjusted. Thereafter, when the wafer W is mounted on the wafer chuck 4Aof the first inspection unit 21A, the position of the wafer transfermechanism 3 is adjusted to correct the eccentricity of the wafer W. As aresult, the direction and the eccentricity of the wafer W are adjusted.The optical sensors 37 and 38 are not illustrated in FIG. 16.

In accordance with this embodiment, the effects to be described belowcan be obtained in addition to the effects of the first embodiment. Thatis, the wafer transfer mechanism 3 incorporates the pre-alignmentmechanism 39 including the chuck portion 36 and the like for performingpre-alignment, so that there is no need to move to the pre-alignmentmechanism 39 after the wafer W is unloaded. Accordingly, the efficiencyof transferring the wafer W increases (the transfer time of the wafer Wis reduced), and the extra space for installing the pre-alignmentmechanism 39 is not required. As a result, the installation areaincrease of the apparatus can be suppressed.

Hereinafter, peripheral units of the pogo pin unit 28 and the mechanismfor replacing the probe card 6A will be described with reference toFIGS. 19 to 21.

The head plate 201 has a pair of guide rails 80 extending in the Ydirection and guiding the probe card 6A between the inspection position(directly under the pogo pin unit 28) for inspecting the wafer W and thereplacement position located outside the housing 22 (the side of theopposite side where the partition wall 20 is positioned). Engaged to theguide rails 80 are end portions of trays 82 configured to move in the Ydirection along the guide rails 80 together with card holders 81 fixedon the trays 82. Moreover, the probe card 6A is clamped to the cardholders 81, and the trays 82 are provided with attaching/detachingmechanisms (not shown) for attaching and detaching the probe card 6A andthe card holders 81 by rotating the probe card 6A and the card holders81 in predetermined directions with respect to the trays 82.

Meanwhile, the pogo pin unit 28 is configured to move vertically byelevators 83 provided at openings of the head plate 201 between theposition of FIG. 19 at which the probe card 6A contacts with the wafer Wand the upper position shown in FIG. 20. In order to replace the probecard 6A, after the pogo pin unit 28 is moved up, the trays 82 need tomove to the replacement position, as illustrated in FIG. 21. Next, theprobe card 6A is separated by rotating the probe card 6A only or theprobe card 6A and the card holder 81 in a predetermined direction.Thereafter, a new probe card 6A is mounted on the trays 82, and ispositioned in a predetermined direction. Next, the new probe card 6A isguided to the inspection position along the guide rails 80 via the trays82 in a reverse sequence of the separation sequence and, then, the pogopin unit 28 is moved down.

When the probe card 6A is replaced, the movement area of the card holder81 and that of the alignment bridge 5A are vertically separated not tointerfere with each other. Further, when the probe card 6A is replaced,the alignment bridge 5A is set to, e.g., a position indicated by a solidline in FIG. 2. Since the alignment bridge 5A and the probe card 6A donot contact with each other, the probe card 6A can be replacedregardless of the position of the alignment bridge 5A. Moreover, thehead plate 201 and the replacement mechanism (the guide rails 80 and thelike) of the probe card 6A are installed as a unit, so that themaintenance can be carried out by opening the head plate 201. In thesame manner, the second inspection unit 21B has a replacement mechanismof the probe card 6B.

The probe card 6A can be replaced by another method other than the abovemethod. To be specific, a transfer table 90 a capable of swinging in ahorizontal direction is provided between the inspection position and thereplacement position, as illustrated in FIG. 22, and the probe card 6Ais replaced by lowering the probe card 6A located at the inspectionposition with the use of a vertically movable replacement member 90 andthen unloading the probe card 6A to the replacement position by swingingthe transfer table 90 a to the outside of the housing 22. In that case,however, it is difficult to perform the maintenance without opening thehead plate 201 and unloading the transfer table 90 a to the outside.Therefore, it is preferable to use the replacement mechanism describedin FIGS. 19 to 21.

Application Example of First Embodiment

Hereinafter, an application example of the first embodiment will bedescried with reference to FIGS. 23 to 26. Further, the description ofthe pre-alignment mechanism 39 will be omitted for simplicity. This isalso applied to following examples.

In an example of FIG. 23, the probe apparatus main bodies 2 inaccordance with the first embodiment are arranged at both sides (in theX direction) of the loader unit 1. The wafer transfer mechanism 3 mayhave three arms 20. However, since the wafer transfer mechanism 3 isshared by four inspection units, by providing five arms (4+1) in thewafer transfer mechanism 3, the wafer transfer mechanism 3 can unloadfour wafers W to load them into four inspection units sequentially.

Accordingly, a plurality of wafers W can be transferred to a pluralityof inspection units by the wafer transfer mechanism 3 having a pluralityof arms. By applying the present invention to the probe apparatus havinga plurality of inspection units, the efficiency of transferring thewafer W can be increased and, also, the throughput of the probeapparatus can be improved. In this case, a plurality of wafers W ofwhich number is smaller by one than the number of arms may be unloadedfrom the carrier C. Moreover, in an example of FIG. 24, there are twopairs of the loader units 1 and the probe apparatus main bodies 2 inaccordance with the first embodiment, wherein the probe apparatus mainbodies 2 are disposed adjacent to each other.

In an example of FIG. 25, a pair of probe apparatuses 300 in accordancewith the first embodiment are arranged to be spaced from each other inthe X direction so that the probe apparatus main bodies 2 face eachother and, also, this pair of probe apparatuses 300 are arranged to bespaced from another pair of probe apparatuses 300 in the Y direction.The space between the probe apparatuses 300 is used as a space formoving a transfer unit (not shown) for transferring the carrier C in aclean room, or as a space for replacing the probe cards 6A and 6B.

In an example of FIG. 26, temperature controllers 60 such as chillers orthe like are installed to be symmetrical with respect to a center pointof the space between the two probe apparatuses 300 arranged in the Xdirection, to thereby control temperatures of the wafer chucks 4A and4B. The temperature controllers 60 are connected with the probeapparatuses 300 via temperature control mediums 61. When such a layoutis employed, it is possible to ensure the space for installing the probeapparatuses 300 in the clean room.

Second Embodiment

The configuration of the second embodiment is the same as that of thefirst embodiment except that the probe apparatus main bodies 2 areconnected to the loader units 1 by rotating the inspection unit 21 by anangle of 90°, so that the moving directions of the alignment bridges 5Aand 5B are perpendicular to the aforementioned moving directions asshown in FIG. 27. Accordingly, the first and the second inspection unit21A and 21B of the second embodiment are symmetrical with respect to thehorizontal line HL, as in the first embodiment.

Moreover, in the probe apparatuses of this embodiment, the probe card 6Ais replaced by the swing method shown in FIG. 22. In that case, thereplacement member 90 of the probe card 6A can contact with thealignment bridge 5A. Therefore, when the probe card 6A is replaced, theprobe apparatus main body 2 is retreated to the position near the loaderunit 1, as can be seen from FIG. 28. A reference numeral 200 indicates areplacement area of the probe card 6A. In the probe apparatus having theconfiguration of FIG. 29, the probe apparatus main bodies 2 can bedisposed at both sides (the X direction) of the loader unit 1, as shownin FIG. 23. In the configuration of the second embodiment, the number ofarms 20 can be increased to five, as described in the first embodiment.

In the above embodiment, there can be provided shutters 120 forindependently opening and closing two transfer openings 22 a on the sidesurfaces of the probe apparatus main body 2, as illustrated in FIGS. 30Aand 30B.

To be specific, the transfer openings 22 a of the loader chamber 1 sideare surrounded by seal members 123 made of resin, and the shutters 120are configured to open and close the transfer openings 22 by elevatingmechanisms 121 via elevating shafts 122. In this example, the effects ofthe atmosphere between the inspection units 21A and 21B or that betweenthe inspection units 21A and 21B and the loader unit 1 can be suppressedby closing the transfer openings 22 a via the seal members 123.

Accordingly, when the wafer W is inspected in one of the inspectionunits 21A and 21B, even if the maintenance, e.g., the replacement of theprobe card 6, is performed in the other inspection unit 21A or 21B, theatmosphere of the inspection is not affected by the atmosphere of themaintenance. Further, even if the atmosphere such as temperatures,humidity and the like in the respective inspection units 21A and 21B ischanged, the wafer W can be inspected while maintaining the atmosphereand suppressing the effects between the atmosphere.

[Another Modification]

In the above example, the wafer chuck 4A has a single micro camera 41and a single micro camera 42, as shown in FIG. 7. However, a pluralityof, e.g., two, micro cameras 70 can be installed so that a pair of microcameras 41 and 42 are provided therebetween (in the X direction), as canbe seen from FIG. 31. The micro cameras 70 as well as the micro camera41 are provided to image the needle tips of the probe needles 29.

In this configuration, since the region where the wafer chuck 4A movesin the X direction in order to image the probe needles 29 can bereduced, the probe apparatus main body 2 can be scaled down. FIGS. 32and 33 show movement strokes D10 and D20 of the centers of the waferchucks 4A and 4B at which the probe needles 29 positioned at both endsin the X direction of the probe cards 6A and 6B are imaged by the singlemicro camera 41 and by three micro cameras in FIG. 31, respectively. Themovement stroke D20 of the latter case is considerably shorter than themovement stroke D10 of the former case. The target 44 and thereciprocating mechanism 43 are not illustrated in FIG. 31.

Further, each of the cameras (the micro cameras 41 and 70) imagesdifferent areas of the probe needles 29, so that it is possible todecrease the moving amount of the wafer chuck 4A at which the probeneedles 29 are imaged.

As can be seen from FIGS. 34A and 34B, the second imaging unit 211having the same configuration as that of the first imaging unit 210including the micro cameras 41 and 42 can be disposed to be symmetricalto the first imaging unit 210 with respect to the center of the wafermounting region on the wafer chuck 4A or 4B. In this example, the microcamera 41 of the first imaging unit 210 is spaced from the micro camera41 of the second imaging unit 211 in the X direction, so that themovement stroke in the X direction of the wafer chuck 4A or 4B isreduced.

Moreover, the micro cameras 41 are spaced from each other in the Ydirection by the diameter of the wafer chuck 4A or 4B, so that themovement stroke in the Y direction of the wafer chuck 4A or 4B isreduced substantially to a half of that obtained in case of providing asingle first imaging unit 210. As a result, the probe apparatus mainbody 2 can be scaled down. In FIG. 34B, the first and the second imagingunit 210 and 211 positioned at both sides (inner side and front side)are respectively indicated as a solid line and a dotted line in order toclarify the positional relationship.

Further, the micro cameras 70 can be provided so that the micro cameras41 and 42 are positioned therebetween (the X-axis side), as shown inFIG. 31.

The above probe card 6A can be used when the contact operation isperformed at a time. In addition, the probe card 6A can be used when thewafer W contacts with the probe needles 29 in two steps by providing theprobe needles 29 in accordance with the arrangement of electrode padgroup divided into two in a diametrical direction of the wafer W, orwhen the wafer W is brought into contact with the area divided into fourin a circumferential direction of the wafer W. In these cases, the probeneedles 29 are brought into contact with the wafer W by rotating thewafer chuck 4A. In the probe apparatus of the present invention, it ispreferable to inspect the wafer W by performing the contact operationonce to four times.

In the above example, the number of the micro cameras 45 is three.However, the number of the micro cameras 45 can be two or four. If thenumber of micro cameras 45 provided is n, the distance therebetween ispreferably set to be 1/n of the diameter of the wafer W.

In the above example, two or three wafers W are simultaneouslytransferred by the three arms 30, thereby reducing time for transferringthe wafers W. However, even if the number of the arms 30 is less thanthree, e.g., one, it is possible to adjust the direction of the wafer Wand correct its eccentricity by the pre-alignment mechanism 39 based onthe direction of loading the wafer W into the inspection unit 21.

When the processing of the wafers W (the fine alignment or theinspection of electrical characteristics) in the probe apparatus mainbody 2 is completed within a preset period of time, each of the wafers Wis sequentially inspected, as described above. However, when theprocessing of the wafer W in the first or the second inspection unit 21Aor 21B is delayed due to the error or the like, it is not possible totransfer a wafer W to be inspected to the first or the second inspectionunit 21A or 21B. In that case, since the wafer transfer mechanism 3 hasthe pre-alignment mechanism 39, the transfer position can be changed aswill be described later and, hence, the processing can be continuedwithout any delay.

A specific example of the above case is described as follows. Althoughthe wafer W to be inspected in, e.g., the first inspection unit 21A ismaintained under the wafer transfer mechanism 3, the processing of thewafer W in the first inspection unit 21A is not completed, whereas theprocessing of the wafer W in the second inspection unit 21B iscompleted.

When the wafer transfer mechanism 3 holding thereon the wafer W unloadedfrom, e.g., the first carrier C1 is lowered, the direction of the waferW held on the wafer transfer mechanism 3 has been adjusted in advancebased on a predetermined transfer position (the first inspection unit21A). Thus, if the transfer position of the wafer W is changed, thedirection of the wafer W is accordingly changed to thereby accommodatethe newly changed transfer position (the second inspection unit 21B) inthe same manner as when the wafer W is unloaded from the carrier C and,then, the wafer W is loaded into the second inspection unit 21B. Bychanging the transfer position when necessary according to the actualwafer processing time, it is possible to reduce the unnecessary timethat the probe apparatus main body 2 waits without performing theprocessing.

Hereinafter, an example of a hinge mechanism of a tester 100 positionedabove the pogo pin unit 28 will be described. FIG. 35 is a top view ofthe tester 100 installed on the probe apparatus main body 2. The tester100 has on its side surfaces L-shaped rotation plates 101. Further, adriving member 103 rotating about a horizontal axis by a motor 102 isprovided between portions of the rotation plates 101 coming out of thetester 100. Moreover, each of the plates 101 has a connection member 104connected to the driving member 103, the connection member 104 beingcapable of moving in the Y direction by a driving unit (not shown). Byadvancing the connection member 104, it can be connected with thedriving member 103 and by retreating the other connection member 104,connection can be released. With this, it is possible to open or closeeach of the testers 100 to contact with the pogo pin unit 28 or beseparated from the pogo pin unit 28 by the motor 102 serving as a commondriving unit.

Hereinafter, an example of the wafer transfer process of the wafertransfer mechanism 3 will be described with reference to FIGS. 36 and37. FIGS. 36 and 37 illustrate a series of sequential processesincluding the unloading of the wafers from the carriers C1 and C2, theloading of the wafers into the inspection units 21A and 21B, theinspection of the wafers W and the return of the inspected wafers to thecarriers C1 and C2. A vertical direction indicates the time elapse, anda left end column represents the processing state. “LotStart” in theleft end column indicates a start of a series of operations includingthe unloading of wafers from the carrier and the inspection of thewafers; “Waf.1Start” indicates a start of the inspection of Waf.1 by thetester; and “Waf.1End” represents a completion of the inspection ofWaf.1 by the tester.

A second column from the left side and the right end column indicateStage 1 and Stage 2, i.e., the states of the wafer chucks 4A and 4B,respectively. “Waf.1” indicates the state where Waf.1 is mounted on acorresponding wafer chuck; “Alignment” represents a state while thecontact position is calculated by imaging the wafer W and the probeneedles 29; and “Test” indicates the state where the wafer is beingtested. For convenience, the numerical reference “Waf.1” or the like isapplied in accordance with the sequence of unloading wafers from thecarriers C1 and C2.

Further, the third to the fifth column from the left side indicate thestates of the upper arm 31, the middle arm 32 and the lower arm 33,respectively. In those columns, “Waf.1” indicates the state where Waf.1is maintained, and “Carrier” represents the state where the wafer thatis being maintained is transferred to the carrier C1 or C2.

Each line indicates the states of the wafer chucks 4A and 4B and thestates of the arms 31 to 33 during a specific period of time, i.e., thesteps of the sequential programs. Namely, FIG. 33 depicts the sequenceof the operation of the apparatus. First of all, the instruction of“LotStart” is given by the control unit 15 (see FIG. 2). Next, Waf.2 andWaf.1 are unloaded from, e.g., the carrier C1, by the upper arm 31 andthe middle arm 32 of the wafer transfer mechanism 3, respectively. Then,Waf.1 is transferred to the stage 1, and, then, Wafer.1 is aligned whileWaf.2 is transferred to the stage 2.

Thereafter, Waf.1 is inspected and, at the same time, Waf.2 is aligned.At this time, the empty three arms 31 to 33 move to the carrier C1 toreceive Waf.3 and Waf.4, and Waf.4 and Waf.3 are mounted on the upperarm 31 and the middle arm 32, respectively. Next, the inspection ofWaf.2 is started and, then, the inspection of Waf.1 is completed. Atthis time, the empty lower arm 33 moves to the stage 1 to receive Waf.1,and transfers Waf.3 mounted on the middle arm 32 to the stage 1.

While Waf.3 is aligned, Waf.1 mounted on the lower arm 33 is restored tothe carrier C1 and, at the same time, the empty middle arm 32 moves tothe carrier C1 to receive Waf.5. Next, the inspection of Waf.3 isstarted, and the inspection of Waf.2 on the stage 2 is completed.Accordingly, the empty lower arm 33 receives Waf.2, and Waf.4 mounted onthe upper arm 31 is transferred to the stage 2. While Waf. 4 is aligned,Waf.2 on the lower arm 33 is returned to the carrier C1 and, at the sametime, the empty upper arm 31 moves to the carrier C1 to receive Waf.6.Thereafter, the inspection of Waf.4 is started. After the inspection ofWaf. 4 is started, the following wafers are transferred and inspected inthe same manner.

As can be seen from the above, in this example, the upper arm 31 and themiddle arm 32 transfer the wafers from the carrier C1 to the stages 1and 2, and the lower arm 33 transfers the inspected wafers from thestages 1 and 2 to the carrier C1.

The steps described in the blocked lower portion of FIG. 36 indicatethat the error occurring in the stage 1 is released by an operator.“Stage1AssistOccur” and “Stage1AssistRelease” correspond to theoccurrence and the release of the error, respectively. The stepsdescribed in the blocked lower portion are continued from the step ofWaf.10Start. Further, FIG. 37 shows steps continued from the steps ofFIG. 36. That is, since these steps are long, one figure is divided intotwo parts. “Stage1ErrorOccur” (separation) in FIG. 37 indicates a statewhere the stage 1 is separated from the system due to the error thatcannot be dealt with the operator.

Further, Initial start and Initial end represent that the initializationis executed to release the error occurring in the stage 1 (theinitialization is executed by manipulating the switch by an operator,and the processing includes the initialization of inner data and theinitialization of the stage relationship). The start of theinitialization is indicated as InitialStart, and the completion of theinitialization is indicated as InitialEnd. “IfWaf.9Tested” and“IfWaf.9UnTested” represent the case where Waf.9 is tested and the casewhere Waf.9 is not tested, respectively. In addition,“Stage1/2SimultaneouslyCleaning” in FIG. 37 indicates the consecutivecleaning of the stages 1 and 2. The cleaning is carried out by polishingthe needle tips of the probe needles by using a NPW (non-product wafer).

FIGS. 38 and 39 depict sequences in case of providing two arms at thewafer transfer mechanism 3 in the apparatus, e.g., the apparatus of thefirst embodiment, for performing the sequences of FIGS. 36 and 37. Ascan be seen from these sequences, in a case where the wafer could not beloaded into the stage 1 or 2 due to an error occurring in the inspectionunit 21A or 21B, i.e., the case where an error occurred in the stage 1or 2, and then, the error has been solved, or in a case where the probeneedles in the inspection unit 21A or 21B are cleaned, a higherthroughput can be obtained in the case where the wafer transfermechanism 3 has three arms than in the case where the wafer transfermechanism 3 has two arms.

FIG. 40 shows an example of the configuration of the control unit 15 ofFIG. 2. A reference numeral 151 indicates a CPU; a reference numeral 152indicates a program for executing a series of processes of the probeapparatus; a reference numeral 153 indicates a recipe storing unit forstoring recipes of the inspection performed in the inspection units 21Aand 21B; a reference numeral 154 indicates a manipulation unit forperforming an operation or setting an operation mode or parameters ofthe probe apparatus; and a reference numeral 155 represents a bus. Themanipulation unit 154 has a display such as a touch panel or the like,and an example of a part of the manipulation display is illustrated inFIG. 41.

In FIG. 41, a reference numeral 160 indicates a soft switch for settinga consecutive lot function forming a wafer unloading function. When thesoft switch 160 is ON, following operations are carried out.

That is, in the case where the wafers in the carrier C1 corresponding toa single lot are sequentially unloaded, if a last wafer to be inspectedis unloaded by, e.g., the middle arm 32, a first wafer to be inspectedin the carrier C2 corresponding to a lot is unloaded by, e.g., the upperarm 31, in a state where the last wafer to be inspected in the carrierC1 is mounted on the middle arm 32. For example, if Waf.9 in FIG. 36 isa final wafer in the carrier C1, Waf.10 corresponds to a first wafer tobe inspected in the carrier C2.

That is, when a wafer of a previous lot (e.g., the carrier C1) ismounted on one of the arms of the wafer transfer mechanism 3, unloadinga wafer of a next lot (e.g., the carrier C2) by using another arm isperformed before the wafer of the previous lot is loaded into theinspection unit. Therefore, a high throughput can be obtained byconsecutively processing different lots.

When the consecutive lot function is not set, a wafer of a next lot(carrier) is unloaded after a wafer of a previous lot (carrier) isloaded into the inspection unit by the arm of the wafer transfermechanism 3.

A reference numeral 161 is a soft switch for setting a consecutiveloading function forming the wafer unloading mode. When the switch 161is ON, following operations are performed. That is, when a wafer in oneof the carriers is mounted on one of the wafer chucks 4A and 4B, if theother wafer chuck is empty, a wafer in the other carrier is loaded ontothe empty wafer chuck. For example, even when a final wafer to beinspected in one of the carriers is inspected in one of the waferchucks, a first wafer to be inspected in the other carrier can be loadedonto the other wafer chuck.

A reference numeral 162 indicates a soft switch for setting a carrierdistribution function. When the switch 162 is ON, a display fordistributing the inspection units for the two loading ports 12 and 13 isdisplayed so that the distribution can be performed. For example, awafer in the carrier on the loading port 12 is transferred to the firstinspection unit 21A, and a wafer in the carrier on the loading port 13is transferred to the second inspection unit 21B.

A reference numeral 163 indicates a soft switch for setting a lotdistribution function. When the switch 163 is ON, wafers aresequentially transferred from the carrier on one of the loading ports 12and 13 to an empty wafer chuck. This function can be applied to both ofthe loading ports 12 and 13, or to any one of the loading ports by usingan additional display.

A reference numeral 164 indicates a soft switch for setting a recipe inthe inspection unit. When the switch 164 is ON, a recipe setting displayis displayed so that a recipe can be set for the respective inspectionunits. A common recipe or different recipes can be set for theinspection units 21A and 21B. The recipe setting includes setting oftemperatures of the wafer chucks, setting for determining whether allthe chips on the wafer will be inspected or only defective chips will beinspected and the like.

A reference numeral 165 is a soft switch for setting a consecutiveinspection function. When the switch 165 is ON, a detailed settingdisplay is displayed, and wafers are transferred from one of theinspection units 21A and 21B to the other inspection unit according to adetermined inspection sequence of the inspection units.

For example, the wafers are inspected in the inspection unit 21A andthen in the inspection unit 21B without being restored to the carrier.In that case, all the chips are inspected in the inspection unit 21A,and only the chips determined to be defective in the inspection unit 21Aare inspected in the inspection unit 21B. In that case, the defectivechips can be marked in the inspection unit 21A. The inspection in theinspection unit 21A can be performed at a first temperature, and theinspection in the inspection unit 21B may be performed at a secondtemperature. When the switch 165 is OFF, the wafer is inspected by onlyone of the inspection units.

A reference numeral 166 indicates a soft switch for setting a waferchuck replacement function. When the switch 166 is ON, if an erroroccurs in one of the inspection units 21A and 21B, the processing can becarried out by the other inspection unit 21A or 21B.

In the present invention, the wafers mounted on the two wafer chucks 4Aand 4B can be simultaneously inspected by a common tester for the twoinspection units 21A and 21B. In that case, the common tester isinstalled separately from the apparatus main body 2, and the probe cards6A and 6B are connected with the common tester via cables.

The following is a description of a preferable example of the secondimaging units mounted on the alignment bridges 5A and 5B shown in FIGS.2, 3 and 5. In the above example, there are provided the three microcameras 45 of high magnification cameras, as depicted in FIG. 14 and thelike. In a following example, however, there are provided two microcameras. Further, since the alignment bridges 5A and 5B have a sameconfiguration, the alignment bridge 5A will be describedrepresentatively. Hereinafter, the X direction (see FIG. 2) indicates aright and left direction, for convenience.

As illustrated in FIG. 42, the alignment bridge 5A has micro cameras301, 302, 401 and 402. The micro cameras 301 and 401 are symmetrical tothe micro cameras 302 and 402 with respect to a central line 300dividing the alignment bridge 5A into a right and a left part. The microcameras 301 and 302 are positioned closer to the horizontal line HL (seeFIG. 2) as a boundary between the first and the second inspection unit21A and 21B, compared to the micro cameras 401 and 402. A distance Ibetween the micro cameras 301 and 302, and the central line 300 isabout, e.g., 73 mm. Further, a distance r between the micro cameras 401and 402 and the central line 300 is about, e.g., 45 mm.

If the above configuration is employed, the movement region of the waferchuck 4A is reduced. In order to align the wafer W with the probeneedles 29, the alignment marks positioned at both end portions of thewafer W are checked by the micro cameras 301 and 302, or the needletraces on the wafer W are checked after the inspection. To do so, bothend portions of the wafer W are positioned directly under the microcameras 301 and 302. FIGS. 43A and 43B depict a movement of the waferchuck 4A during the above operation. As can be seen from FIG. 43A, thewafer W is positioned under the alignment bridge 5A so that the centralline 300 of the alignment bridge 5A coincides with the center C of thewafer W. In order to image the left region of the wafer W by the microcamera 301, the wafer chuck 4A needs to move in the X direction so thatthe left end portion of the wafer W can be positioned directly under themicro camera 301 as illustrated in FIG. 43B. At this time, the movingamount of the wafer chuck 4A in FIG. 43A corresponds to M1. If the waferW has a diameter of about 300 mm, M1 is about 77 mm.

FIG. 44 illustrates the entire moving amount of the wafer W in the Xdirection. In a state where the center C of the wafer W is positioned onthe central line 300 of the alignment bridge 5A, the moving amount ofthe wafer W to the right or the left area corresponds to M1, as shown inFIG. 44. Since the wafer W having a diameter of about 300 mm is used inthis example, M1 is about 77 mm, and the entire moving amount of thewafer W is about 154 mm.

FIG. 45 shows a case where a single micro camera 301 is attached to thealignment bridge 5A. In that case, after the center of the wafer W ispositioned directly under the micro camera 301, left or right endportion of the wafer W is positioned directly under the micro camera 301by moving the wafer chuck 4A in the X direction. Therefore, the movingamount M2 of the wafer W to the right or the left area corresponds to aradius of the wafer W, as depicted in FIG. 45. Since the wafer W havinga diameter of 300 mm is used in this example, M2 is about 150 mm, andthe entire moving amount of the wafer W is about 300 mm.

A plurality of points on the wafer W are imaged to obtain a relationshipbetween ideal coordinates on the wafer W (coordinates of an electrodepad of each chip which has an origin of the wafer center) and actualcoordinates in the driving system of the wafer chuck 4A (the number ofpulses of the encoder in the motor which is required to move the wafer Wby a specific amount in the X and Y directions). The plurality of pointscorrespond to five points including, e.g., the center of the wafer W andfour alignment marks positioned on the circumference of the chip wherethe circumference intersects with dicing lines passing through thediameters of the wafer W in the X and Y directions. Imaging the fivepoints for the alignment is assigned to the micro cameras 301 and 302,so that the moving amount or the moving time of the wafer chuck 4A canbe reduced compared to the case of using a single micro camera.

Hereinafter, the method for using the micro cameras 401 and 402 will bedescribed with reference to FIGS. 46 to 48. Referring to FIG. 46, thecoordinates of four points E1 to E4 of the wafer W are obtained byimaging the four points E1 to E4 and, also, an intersection pointbetween a line connecting two points E2 and E4 and a line connecting twopoints E1 and E3 is obtained. This intersection point corresponds to acentral point (central coordinates) C of the wafer W. Further, thelength of the line connecting the points E1 and E3 (or the points E2 andE4) corresponds to a diameter of the wafer W.

Even when the wafer W has a diameter of, e.g., 300 mm, the actualdiameter of the wafer W may be slightly different. In order to obtain aprecise map (the coordinates of the electrode pads) of the chips on thewafer W, the coordinates of the center of the wafer W and the diameterof the wafer W need to be calculated. Moreover, one more reason forobtaining the coordinates of the center of the wafer W is because theregistered positions of the electrode pads of the chips on thecoordinates on the wafer are stored as relative positions with respectto the coordinates of the center of the wafer W.

As shown in FIG. 46, the points E2 and E3 are spaced from each other bya predetermined distance. The points E1 and E4 correspond to theintersection points obtained by moving a segment between the points E2and E3 in the Y direction by way of moving the wafer W in the Ydirection so that the segment can meet the circumference of the wafer W.In this example, the positions of the points E2 and E3 are obtained bysequentially imaging lower right and left portions of the wafer W inFIGS. 47A and 47 B with the use of the micro cameras 401 and 402, as canbe seen from FIGS. 47A and 47B. Next, the wafer W moves in the Ydirection and, then, upper right and left portions of the wafer W aresequentially imaged by the micro cameras 401 and 402, as described inFIGS. 48A and 48B. As a result, the positions of the points E1 and E4are obtained.

Meanwhile, if there is provided a single micro camera, the chuck needsto move to positions corresponding to the four points on the wafer Wsequentially. However, in this example, a pair of the two points E1 andE3 (or E2 and E4) can be almost simultaneously checked by shifting themicro cameras 401 and 402. Therefore, the wafer chuck 4A needs to movein the Y direction only once, after the two points E1 and E3 arechecked. Accordingly, the four points on the circumference of the waferW can be imaged in a short period of time. When the two micro cameras401 and 402 are used, they are preferably provided to be symmetricalwith respect to the central line 300. This is because when imaging theright and the left region of the wafer W is assigned to the microcameras 401 and 402, the movement region of the wafer chuck 4A becomessymmetric with respect to the central line 300. Therefore, if thismovement region is overlapped with the movement region in which thewafer W is imaged by the micro cameras 301 and 302, the movement regionof the wafer chuck 4A is reduced compared to that obtained when they areasymmetric. The arrangement of the micro cameras 401 and 402 may beasymmetric with respect to the central line 300.

The micro cameras 301 and 302 have magnification converters provided onan optical path of an optical system. By controlling the magnificationconverters, it is possible to obtain a view (middle view) slightlysmaller than the magnification of the high magnification camera. Themagnification of the high magnification camera enables a needle trace ona single electrode pad to be checked. When the operator needs to checkthe needle trace on the electrode pad after the inspection, the needletrace cannot be seen by the micro cameras 401 and 402. Moreover, theelectrode pads can be checked only one by one by the micro cameras 301and 302, requiring a long period of time. Accordingly, a plurality ofelectrode pads can be monitored at a time by the middle view, and theexistence/non-existence of the needle trace can be effectively checked.Such a middle view can also be used for imaging, e.g., the five pointsfor alignment on the wafer W.

As set forth above, when two pairs of micro cameras are used, the movingamount of the wafer chuck 4A at which the wafer W is aligned with theprobe needles 29 decreases compared to the case of using one pair ofmicro cameras. As a consequence, a throughput can be improved and, also,the apparatus can be scaled down. In case of the apparatus that themoving amount of the wafer chuck is small, it is not possible to checkthe entire wafer by one pair of micro cameras. However, the presentinvention can be applied to such apparatus by using two pairs of microcameras.

Test Example

The following is a comparison of the operation sequence of the wafertransfer mechanism 3 in exchanging the wafers W which has been describedin the first embodiment between where three arms 30 are provided (thepresent invention) and where two arms 30 are provided (the conventionalexample). Further, other configurations are the same except for thenumber of arms 30.

As set forth above, when three arms 30 are provided, the wafers W can betransferred sequentially and consecutively to and from the first and thesecond inspection unit 21A and 21B without accessing the cassette C orthe pre-alignment mechanism 39. Meanwhile, when two arms 30 areprovided, there arises a need to access the cassette C or thepre-alignment mechanism 39 before a wafer W is transferred to the secondinspection unit 21B in case where a wafer has been loaded into the firstinspection unit 21A. FIGS. 49A to 50G schematically depict the operationof the wafer transfer mechanism 3. FIGS. 49A to 49F and FIGS. 50A to 50Gdescribe the case where the number of arms 30 is three and the casewhere the number of arms 30 is two, respectively. FIG. 49A to 49F andFIG. 50A to 50G respectively indicate the sequence of the treatment(transfer) of the wafer W. Hereinafter, the operation of the wafertransfer mechanism 3 in exchanging the inspected wafers W1 and W2respectively mounted on the wafer chucks 4A and 4B with the wafers W3and W4 to be inspected will be described in detail.

As illustrated in FIGS. 49A to 49F, when there are provided three arms30, the wafers W3 and W4 to be inspected are transferred by, e.g., theupper and the middle arm 31 and 32, respectively (FIG. 49A). At thistime, the pre-alignment process or the OCR process is performed on thewafers W3 and W4 before the inspection of the wafer W1 mounted on thewafer chuck 4A is completed. When the inspection of the wafer W on thewafer chuck 4A is completed, the inspected wafer W1 is unloaded by,e.g., the lower arm 33 (FIG. 49B). Next, the wafer W3 of the upper arm31 is mounted on the wafer chuck 4A (FIG. 49C). Thereafter, theinspected wafer W2 on the wafer chuck 4B is unloaded by the upper arm 31(FIG. 49D) and, then, the wafer W4 of the middle arm 32 is mounted onthe wafer chuck 4B (FIG. 49E). As a result, the inspected wafers W1 andW2 are unloaded by the wafer transfer mechanism 3, and the wafers W3 andW4 to be inspected are loaded on the wafer chucks 4A and 4B so as to beinspected (FIG. 49F). That is, the wafer transfer mechanism 3 isprovided with the three arms 30 and two wafers W to be inspected aresupported by the three arms 30, so that the to-be inspected wafers W canbe sequentially transferred to the first and the second inspection units21A and 21B.

Meanwhile, when there are provided two arms 30, the wafer W3 to beinspected is transferred by, e.g., the upper arm 31, as illustrated inFIG. 50A. At this time as well, the pre-alignment process or the OCRprocess is performed on the wafer W3 before the inspection of the waferW1 on the wafer chuck 4A is completed. When the inspection of the waferW1 on the wafer chuck 4A is completed, the inspected wafer W1 isunloaded by the lower arm 33 (FIG. 50B). Next, the wafer W3 of the upperarm 31 is mounted on the wafer chuck 4A (FIG. 50C).

Thereafter, the wafer transfer mechanism 3 moves up to a position wherethe wafer is transferred to/from the carrier C. Then, the wafer W1 isreturned to the carrier C and, at the same time, a next wafer W4 isunloaded by, e.g., the upper arm 31. Next, the pre-alignment process orthe OCR process (access to an OCR cassette) is performed on the wafer W4(FIG. 50D). Thereafter, the wafer transfer mechanism 3 moves to a wafertransfer position (FIG. 50E), and the inspected wafer W2 mounted on thewafer chuck 4B is unloaded (FIG. 50F). Next, the wafer W4 of the upperarm 31 is mounted on the wafer chuck 4B (FIG. 50G).

FIG. 51 schematically shows elapsed time of transferring the wafers tobe inspected W1 and W2 in accordance with the operation of the wafertransfer mechanism 3. In FIG. 51, (1) indicates the case where threearms 30 are provided, and (2) represents the case where two arms 30 areprovided. In FIG. 51, “1st/2nd Wafer”, “1st Wafer”, “2nd Wafer” and “3rdWafer”, denoted in the second column from the left, indicate wafers tobe processed. Moreover, types of processes to be performed on the wafersW are indicated in the right side thereof.

In FIG. 51, the processes corresponding to FIGS. 49A to 49F and FIGS.50A to 50G are indicated by the corresponding Figure numerals. Further,a horizontal axis in FIG. 51 indicates an elapsed time. FIG. 51illustrates the pre-alignment process that is omitted in FIGS. 49A to50G. In FIG. 51, “Shutter” indicates a process for opening a shutter(not shown) provided at the transfer port 22 a of the inspection units21; “Alignment” indicates a fine alignment process performed in theinspection units 21; “Wafer Load” indicates a process of loading thewafer W into the inspection unit 21; “Wafer Unload” indicates a processof unloading the wafer W from the carrier C; and “Front(Rear) Stage”represents the wafer chuck 4A (4B).

As can be seen from FIG. 51, by increasing the number of arms 30 fromtwo to three, the efficiency of transferring the wafer W increases and,hence, a period of time required to transfer the wafers W is reduced.Further, it is possible to reduce a period of time required from thestart of the operation to the completion of the loading of two wafers Winto the inspection units 21 and that required from the start of loadingof the first wafer W1 to the completion of the loading of the secondwafer W2. Therefore, the throughput of the probe apparatus can beimproved by increasing the number of arms 30 to three. Further, in (2)of FIG. 51, the example of the operation of two arms 30 shows wafers W1,W2 and W3 in separate stages. In addition, when the wafers W areexchanged as described in FIGS. 50A to 50G, extra time is required toreturn the wafer W1 to the carrier C, as can be seen from the lowermoststage in FIG. 51.

While the invention has been shown and described with respect to theembodiments, it will be understood by those skilled in the art thatvarious changes and modification may be made without departing from thescope of the invention as defined in the following claims.

1. A probe apparatus for inspecting a plurality of chips arranged on asubstrate by mounting the substrate on a horizontally and verticallymovable substrate mounting table and then contacting probes of a probecard with electrode pads of the chips, the probe apparatus comprising: aload port for mounting therein a carrier having therein a plurality ofsubstrates; a plurality of probe apparatus main bodies, each includingthe probe card having the probes on its bottom surface; a substratetransfer mechanism for transferring the substrate between the load portand the probe apparatus main bodies, the substrate transfer mechanismbeing rotatable about a vertical axis and movable up and down; and acontrol unit for outputting a control signal to the probe apparatus mainbodies and the substrate transfer mechanism, wherein the substratetransfer mechanism has at least three substrate supporting members, thenumber of the substrate supporting members being greater than that ofthe probe apparatus main bodies by one, each substrate supporting memberbeing independently movable back and forth, and the control unit outputsa control signal for receiving at least two substrates to be inspectedfrom the carrier by the substrate transfer mechanism and sequentiallyreplacing the substrates with inspected substrates in the probeapparatus main bodies by using an empty substrate supporting member. 2.The probe apparatus of claim 1, wherein the substrate transfer mechanismincludes a pre-alignment mechanism having a rotation unit which rotatesa substrate received from the substrate supporting members and adetection unit which irradiates light to a region including acircumferential edge portion of the substrate on the rotation unit andreceives light passing through the corresponding region in order toposition-align the substrate, the detection unit being fixed to a baseof the substrate transfer mechanism.
 3. The probe apparatus of claim 1,wherein the control unit controls the substrate supporting members suchthat one of the substrate supporting members unloads one of thesubstrates from the carrier while another of the substrate supportingmembers keeps another substrate of the substrates after unloading saidanother substrate from the carrier and before loading said anothersubstrate into the probe apparatus main body.
 4. The probe apparatus ofclaim 2, wherein the control unit controls the substrate supportingmembers such that one of the substrate supporting members unloads one ofthe substrates from the carrier while another of the substratesupporting members keeps another substrate of the substrates afterunloading said another substrate from the carrier and before loadingsaid another substrate into the probe apparatus main body.